Hepatic glycogen synthetase deficiency. Further studies on a family.

A family with hepatic glycogen synthetase deficiency originally studied in 1962, was restudied 7 years later. Blood glucose concentrations were measured after glucagon administration, and both blood glucose and plasma cortisol were measured during periods of prolonged fasting and isocaloric carbohydrate-free diets. The twins on whom the original diagnosis was made had an improved ability to maintain a normal blood glucose concentration, but still had episodes of hypoglycaemia; their ability to store glycogen in the liver remained extremely poor. Two sibs still had both frequent episodes of hypoglycaemia, and a diminished capacity to convert glucose to glycogen; their ability to store glycogen in the liver was variable. A third sib was normal. No decrease in plasma cortisol concentrations was noted at any time in any of the children. An increase in blood lactate concentrations after oral administration of glucose, and more particularly, of galactose, is a useful test in the differential diagnosis of hepatic glycogen synthetase deficiency. For definitive diagnosis a liver biopsy with assay of individual enzymes is essential.